For the postgres config, set fsync=off and full_page_writes=false, and increase min_wal_size, max_wal_size and checkpoint interval with the hope that your tests pass before having to flush the WAL. Maybe slap in some tunings from PGTune.

If you're using docker/podman or docker-compose and your db size is small, a major speedup on linux is to just mount the entire data dir into memory with --tmpfs /var/lib/postgresql/data (or tmpfs: - /var/lib/postgresql/data in docker-compose)

Additionally, if you constantly reset your db in the tests, consider making a template db at the start and later just doing CREATE DATABASE ... TEMPLATE foo; to copy the pages from that template instead of running migrations that produce WAL log. In fact, consider making a db for every test suite from that template at the start - then you can run each suite in parallel (if your app's only state is the db and a single backend).